Process for producing non-conjugated dienes



United States Patent 3,475,509 PROCESS FOR PRODUCING NON-CUNJUGATED DIENES Go Hata and Akihisa Miyake, Kamakura-shi, Japan, as-

signors to Toyo Rayon Kabushiki Kaisha, Chuo-ku, Tokyo, Japan, a corporation of Japan No Drawing. Filed Sept. 15, 1967, Ser. No. 668,213 Claims priority, application Japan, Sept. 19, 1966, 41/61,479; Oct. 3, 1966, 41/ 64,844 Int. Cl. C07c 11/12 US. Cl. 260680 22 Claims ABSTRACT OF THE DISCLOSURE A process for producing non-conjugated dienes which comprises reacting conjugated diolefinic hydrocarbons with ethylene in the presence of a catalyst consisting of iron complexes of diphosphine or iron complexes of diphosphine and organoaluminum compounds. The iron complexes of diphosphine are selected from those represented by the general formula:

wlierein R is a hydrogen atom, a methyl group, or an ethyl group; n stands for 2 or 3; and R is a hydrogen atom or a hydrocarbon group having 1 to 6 carbon atoms; and complexes of the formula:

wherein R and n are as defined above.

3,475,509 Patented Oct. 28, 1969 ene, are compounds having various valuable uses as intermediates. Recently, 1,4-hexadienes have been attracting attention particularly as a third component for imparting sulfur vulcanizability to an ethylene-propylene copolymer, a so-called ethylene-propylene rubber.

However, most of the processes for producing nonconjugated dienes not only required a great number of processing steps, but also the cost of the starting material was high. Thus, the economic value of these processes was low. Recently, there is disclosed in French Patent 1,319,578 a process of producing hexadienes from ethylene or propylene and butadiene. The catalyst used in this process, however, is a very costly one such as rhodium trichloride, and hence the cost of production becomes inevitably high.

As a result of extensive studies about a process for effectively achieving said addition reaction, the present inventors have succeeded in developing a catalyst capable of producing non-conjugated dienes with high selectivity and at high yield, thereby having reached the present invention.

The catalyst used in the process of the present invention is an iron complex of diphosphine represented by the general formula (wherein R stands for hydrogen atom, methyl group or ethyl group, It stands for 2 or 3, and R stands for hydrogen atom or a hydrocarbon group having 1 to 6 carbon atoms), or an iron complex of diphosphine represented by the general formula The iron complexes of diphosphine represented by the aoove Formulae 1 and 2 are novel substances which have been synthesized by the present inventors for the first time and process for producing them will be described in detail later.

A more highly active catalyst used in the process of the present invention is the one obtained by mixing the iron complexes of diphosphine represented by the above general formulae with organoaluminum compounds.

An organoalumium compound as herein referred to is an alkylaluminum and an alkyl aluminum halide. Especially, organoaluminum compounds represented by general formulae R" Al, A" AlX, R" Al X and R"AlX (wherein R" stands for an alkyl group having l-8 carbon atoms and X stands for a halogen atom) are preferably used. As examples thereof, triethylaluminum, trisobutylaluminum, diethylaluminum chloride, di-n-propylaluminum chloride, diisobutylaluminum chloride, ethylaluminum sesquichloride, ethylaluminum sesquibromide, ethylaluminum dichloride and n-hexylaluminum dichloride may be cited.

The process of the present invention comprises contacting, in the presence of a catalyst consisting of the said iron complex of diphosphine or a catalyst consisting of the said iron complex of diphosphine and the said organoaluminum compound, conjugated diolefinic hydrocarbons with ethylene to prepare non-conjugated dienes wherein ethylene is added to a carbon atom at position 1 or 4 of the said conjugated diolefinic hydrocarbon.

The conjugated diolefinic hydrocarbons as hereinabove referred to are unsubstituted or substituted 1,3-butadiene represented by the general formula R1 Ra a l a (wherein R R R and R stand for hydrogen atom or a hydrocarbon group having 1 to 6 carbon atoms).

As examples of conjugated diolefinic hydrocarbons especially preferably used, 1,3-butadiene, 2-methyl-l,3- butadiene, 2,3-dimethyl-1,3-butadiene, l,4-dimethyl-l,3- butadiene, 2,4-dimethyl-1,3-butadiene, and 2-phenyl-1,3- butadiene may be cited.

There are two modes of addition of ethylene to the said conjugated diolefinies. One is a case where one hydrogen atom of ethylene is bonded to a carbon atom at In cases where mono-substituted conjugated diolefins are involved, it can be said that ethylene is apt to attach that terminal carbon atom which has a substituent rather than that without a substituent.

An amount of the catalyst used is an ordinary one, the so-called catalytic amount will suffice. In case of using an iron complex of diphosphine alone, it is preferable to use it in an amount of 0.01 to 1 mol percent based on the said conjugated diolefinic hydrocarbons. in a binary catalyst consisting of an iron complex of diphosphine and an organoaluminum compound, a small amount of the iron complex of diphosphine sufiices and it is preferable to use it in an amount of 0.00001 to 0.01 mol percent based on the said conjugated diolefinic hydrocarbons.

In cases where a binary catalyst consisting of an iron complex and an organoaluminum compound is used, there is no particular limitation concerning the ratio of the two components. However, ordinarily it is preferable to use the organoaluminum compound in an amount of 1 to 50 mols based on 1 mol of the iron complex. In cases where the said organoaluminum compound is R" Al X or R"AlX 1 to 4 mols are particularly preferable, and in cases where the said organoaluminum compound is R" AlX or R Al at least 4 mols are particularly preferable.

It is operationally convenient to dissolve catalyst components in an organic solvent which is inert to the catalyst, for instance, benzene, toluene, xylene, etc. In the case of a binary catalyst, a particularly high catalytic activity is obtained, when mixing of the two components is carried out in which is itself one of the reactants, a conjugated diolefinic hydrocarbon.

As to the contact temperature of the present invention, a range of 0l50 C., especially, 40l00 C. is preferable. Also it is preferable to carry out the reaction under pressure of ethylene. Especially when the reaction is carried out under ethylene pressure of 20-60 kg./cm. the reaction proceeds fast.

The desired non-conjugated dienes can be synthesized by the invention process by suitably varying the conditions within the ranges indicated hereinabove of the present invention. For example, the relationship between the kinds of the conjugated diolefinic hydrocarbons used and the resulting non-conjugated dienes is, in general, as follows.

(1) 1,3-butadiene- 1,4-hexadiene, 1,5-hexadiene (2) 2-alkyl-l,3-butadiene- 5-alkyl- 1 ,4-hexadiene, 4-alkyl- 1,4-hexadiene (3) 4-alkyl-l,3-butadiene 3-alky1-l,4-hexadiene, 6-alkyl- 1,4-hexadiene, 3-alkyl-1,5-hexadiene (4) 2,3-dialkyll,3-butadiene 4,5 -dialkyll ,4-hexadiene (5) 2,4-dialkyl-2,4-hexadiene 4,6-dialkyl-1,4-hexadiene,

3,5-dialky1-1,4-hexadiene (6) 1,4-dialkyl-l,3-butadiene 3,6-dialkyl-1,4-hexadiene (7) Z-phenyll ,3-butadiene 4-phenyl-1,4-hexadiene In accordance with the process of the present invention, from a conjugated diolefine and ethylene, a non-conjugated diene is obtained in a high yield.

Also by combining the iron complexes of diphosphine with the said organoaluminum compounds, it is possible to produce 1,4-dienes with a very high selectivity (above which can be maintained even at very high conversion (above 95%) of the conjugated diolefines. Such a high selectivity as observed in the catalyst system of this invention has never been expected from the conventional catalysts. Namely, in the method of US. Patent 3,152,- (British Patent 948,041) using rhodium chloride as a catalyst, the selectivity of production of 1,4-dienes is about 85%, while in French Patent 1,388,305 using a nickel-phosphine complex, the selectivity is only 80%.

Furthermore, they have disadvantages in that the selectivity is remarkably lowered when the conversion of the conjugated diolefins is raised. Thus, the above-described selectivity of the catalyst according to the said US. patent is attainable at the conversion below 60%, and that of the catalyst according to the said French patent only at the conversion below 25%. According to the method described in the said French patent, for example, the selectivity is as low as 19% at the conversion of 35%. In each of the conventional catalyst systems hereinabove described, the amount of a by-product, 2,4-hexadiene, increases and the selectivity in 1,4-hexadiene formation is lowered, when the conversion is raised further.

Next, an explanation will be made with reference to the iron complexes of diphosphine represented by the said Formula 1 or 2 which are used as catalyst or catalyst component in the present invention. These complexes are novel substances which have been synthesized by the present inventors for the =first time, and processes for preparing the same will be described below.

The said iron complexes of diphosphine may be prepared by the reaction of a divalent or trivalent iron compound with an alkylaluminum compound in the presence of a diphosphine represented by the general formula R il Q (wherein R and n are the same as defined above) and an u-olefine represented by the general formula CH =CHR (wherein R is the same as defined above).

As typical examples of the starting diphosphines, 1,2- bis(diphenylphosphino)ethane, 1,3 bis(diphenylphosphino) propane and 1,2-bis(ditoly1phosphino)ethane may be cited.

As examples of the said u-olefins, ethylene, propylene, l-butene, l-pentene, l-hexene and styrene may be cited, of which ethylene is the most preferably used.

As the iron compound, a compound having an ironoxygen bond is preferably used. Especially, a chelated iron compound of B-diketoues such as iron (II) acetyl acetonate, iron (III) acetylacetonate and iron (III) benzoylacetylacetonate, a chelated iron compound of a ketocarboxylic acid ester such as iron (III) ethylacetoacetate and an iron carboxylate such as ferric formate, ferrous acetate, ferric acetate and ferric dimethoxyacetate may be cited.

An alkylaluminum compound is used for the reduction of the said iron compounds. As such a compound, the compounds wherein at least two alkyl groups are directly bonded to the aluminum atom, namely, ROAlR' AlR' and MAlR"' (wherein R and R stand for an alkyl group having 1 to 8 carbon atoms and M stands for an alkali metal) are used. As typical examples of such an organoaluminum compound, an alkoxydialkyl aluminum such as ethoxydiethylaluminum, ethoxydiisobutylaluminum, and alkoxydialkyl and butoxydiethylaluminum; a trialkylaluminum such as triethylaluminum, diethylisobutylaluminum and triisobutylalurninum; and tetraethylaluminum sodium may be cited.

When the said starting materials are mixed and contacted, the desired complex can easily be obtained.

In this case, it is preferable to contact an iron component with an organoaluminum compound in the presence of a diphosphine. Otherwise, the desired complex cannot be preferably obtained, because a reduced iron cannot remain stable.

As a reaction medium, an inert solvent, such as benzene, toluene and diethyl ether are preferably used.

The reaction is carried out in the presence of an ocolefin preliminarily dissolved in these solvents or while passing the a-olefin through a solution of the reaction vessel.

In case where an alkyl aluminum compound with at least one straight-chain alkyl group of 2 to 8 carbon atoms directly bonded to an aluminum atom is used, an u-olefine having the corresponding number of carbon atoms is sometimes produced during the reaction depending upon the reaction conditions. In that case, the preliminary presence of an a-olefine in the reaction vessel is not requisite.

As to the reaction temperature of preparing the catalyst, a range of 30 C. to 150 (1., especially 5 C. to C. is preferable.

With reference to the ratio of the starting materials, there is no particular limitation, but the molar ratio of 1 to 4, especially a stoichiometric amount of about 2 mols of diphosphine per mol of the iron compound is preferable, and a range of molar ratio of an organoaluminum based on an iron compound is 1 to 50, especially 3 to 10 is preferable.

At reaction temperatures below 60 C., an iron complex having the said general Formula 1 is obtained, while above 60 C. an iron complex having the said general Formula 2 is obtained. In order to obtain the iron complex of the said Formula 2 in a good yield, it is preferable to mix the said starting materials at a temperature below 40 C. and then to heat the reaction mixture to 60-100 C. However, the separated complex having the said general Formula 1 does not convert into an iron complex having the general Formula 2 at this temperature range. The iron complex of the said general Formula 2 may be easily obtained also by irradiating the iron complex of the said general Formula 1 with ultraviolet ray.

The iron-diphosphine complexes prepared by such methods are all crystalline solids and very unstable in the air. Therefore, preparation of the said iron complexes is ordinarily carried out under the non-oxidizing atmosphere.

Next, the present invention will be explained in further detail with reference to examples. However, it should be noted that the present invention will not be limited to these examples.

EXAMPLE 1 1 Production of F6 s s 2 2 2 s s 2] 2 2 4 Into a 500 cc. 3-necked flask, the air inside of which was replaced by argon, 11.9 g. (0.030 mol) of powdery 1,2-bis(diphenyl phosphino) ethane, 5.3 g. (0.015 mol) iron (III) acetyl acetonate and 250 cc. of ethyl ether (whose moisture and air were completely removed) were charged. Next, 15 cc. of ethoxydiethylaluminum was dissolved in cc. of ethyl ether and the mixed solution was gradually added dropwise to the said flask with stirring. The period required for dropping was 2.5 hours. When the entire mixture was further stirred at 0 C. for 30 minutes and at room temperaturre for 1 hour, violet crystals were separated, which were filtered and Washed with ether. As a result, 11.2 g. of

was obtained. The melting point of the product was C. (decomposition).

The product was identified as Fe[ (Cs 5)2 a 2 6 5) 2] z 2 4 as follows.

Elemental analysis calculated value: C, 73.64; H, 5.95. Observed value: C, 73.58, H, 6.03.

It reacted with 1 mol of iodine to give al s s )2 2 2 s s 2] (C6H5)2PCH2CH2P(C6H5) 2 and ethylene.

(2) Production of a non-conjugated diene Into a 100 cc. autoclave 30 cc. of toluene, 0.440 g. of

2[ s- 5) 2 2 2 s s 2] 2 2 4 obtained above and 26 cc. of liquified butadiene were charged, and the resultant mixture was stirred at 85 C. under ethylene pressure of 40 kg./cm. for 6 hours. As a result, 2.3 g. of 1,5-hexadiene, 2.6 g. of 1,4-hexadiene, 1.4 g. of 1,3-hexadiene, 1.4 g. of 2,4-hexadiene and 7.7 g. of diene having 8 carbon atoms were obtained.

EXAMPLE 2 Into a 100 cc. autoclave, 30 cc. of benzene, 0.440 g. of

l s 5)2 2 2 s e) 2] 2 2 and 24.6 g. of 1,3-hexadiene were charged and while keeping pressure of ethylene at 40 kg./cm. the entire mixture was stirred at 85 C. for 6 hours. As a result, 5.8 g. of diene having 8 carbon atoms, containing 2.6 g. of 3-methyl-l,5-heptadiene was obtained.

EXAMPLE 3 Into 50 cc. of diethyl ether, 0.35 g. of iron (III) acetylacetonate and 0.8 g. of l,2-bis(diphenyl phosphino) ethane were suspended, while passing an ethylene gas, 1.55 cc. of ethoxydiisobutylaluminum dissolved in 20 cc. of ether was added thereto. As a result 0.4 g. of

was obtained, which identified by the same method as described in Example 1.

Into a 100 cc. autoclave, 26 cc. of liquefied butadiene was charged to which 0.44 g. of

obtained by the aforementioned process dissolved in 10 cc. of toluene was added. Further, 8 cc. (8 mmol) of a toluene solution of (C H AlC1 was added thereto. The entire mixture was heated to 50 C. and while keeping the pressure of ethylene at 40 kg./cm. stirring was continued for 30 minutes. As a result 21.2 g. of 1,4-hexadiene was produced. The reaction residue was 0.7 g. Conversion: 93.10 (mol) percent. Selectivity: 96.30- (mol) percent.

EXAMPLE 4 Into a 100 cc. autoclave, 30 cc. of toluene, 0.440 g. of

1( s s)2 z 2 s 5)2]2' 2 4 16.4 g. (0.2 mol) of 2,4-hexadiene and 2 cc. of a toluene solution containing 2 mmols of triethylaluminum were charged. Ethylene was introduced up to a pressure of 40 solution containing 4 mmols of diethylaluminum chloride were charged. An ethylene gas was introduced up to a pressure of 40 kg./crn. and the entire mixture was stirred at 80 C. for 1 hour. As a result, 16.1 g. of 3,5-dimethyl- 1,4-hexadiene and 1.4 g. of 4-methyl-l,4-heptadiene were obtained. Conversion: 95 (mol) percent. Selectivity: 95 (mol) percent.

EXAMPLE 7 s s 2 Z 2 2 s s 2] 2' 2 4 was obtained.

Element analysis: Calculated values C, 74.00; H, 6.16. Observed values C, 74.26; H, 6.27.

Into a 100 cc. autoclave, 26 cc. of liquefied butadiene was charged to which 0.447 g. of

1 s s) 2 2 2 2 s s) 2] 2 2 4 dissolved in 20 cc. of toluene was added. Further, 2 cc. of a toluene solution containing 2 mmols of diethylaluminum chloride was added. The reaction temperature and pressure of ethylene were kept at 80 C. and 40 kg./cm. respectively, and the entire mixture was stirred for 30 minutes. As a result, 23.8 g. of 1,4-hexadiene was obtained. The residue was 0.6 g. Conversion: 100. Selectivity: 96.66.

EXAMPLES 8-11 Into a 100 cc. autoclave, 26 cc. of liquefied butadiene, 20 cc. of toluene and 0.5 mmol of the following iron complexes prepared by processes similar to the one in Example 3 in the presence of the corresponding a-olefins were charged. Then, 2 cc. of a toluene solution containing 2 mmols of diethylaluminum chloride was added. While the reaction temperature and pressure of ethylene were kept at 80 C. and 40 kg./cm. respectively, the entire mixtures were stirred for 30 minutes to obtain results shown in the following table.

1,4-l1exa- Residue Conversion Selectivity Example diene (g.) (g.) (mol) percent (mol) percent 8... FQ[(PCII3CBH4)2POH2CH2P(PCH3CQH4 Z]Z.C2I'I4 20. 3 0. 4 84. G6 97. 28 9.. Fe[(CsH5) 2PCH2CHzP(CsH 212- CHZ=CHCH 19. 9 0. 6 84. 33 95. 65 10 Fe[(CaH zPCHzCHzP (OuHQz 2- CH2=CHCH2CH;CH; 23. 1 0. 9 99. 33 07. 65 F0[(C5H5) zPCHzCHzP (CnH5)2 2' CH2=CHC 1H5 21. 8 0. 7 92. 67 95. (S8

kg./crn. and the entire mixture was stirred at 80 C. for 6 hours. As a result, 5.8 g. of 3-methyl-l,4-heptadiene was obtained.

EXAMPLE 5 Into a 100 cc. autoclave, 20 cc. of toluene, 0.440 g. of

F e 6 5)2 2 2 s 5)2] 2' 2 24.6 g. of 2,3-dimethyl-1,3-butadiene and 4 cc. of a toluene solution containing 4 mmols of diethylaluminum chloride were charged. The pressure of ethylene was kept at 40 kg./cm. and the entire mixture was stirred at 80 C. for 1 hour. As a result, 33.0 g. of 4,5-dimethyl-1,4-hexadiene was obtained. Conversion: 100 (mol) percent. Selectivity: 98 (mol) percent.

EXAMPLE 6 Into a 100 cc. autoclave, 20 cc. of toluene, 0.440 g. of

14.5 g. of 4-methyl-l,3-pentadiene and 4 cc. of a toluene Confirmation of production of catalysts was carried out as follows:

Element analysis: Calculated values C, 75.43; H, 5.91. Observed values C, 75.22; H, 5.83.

9 EXAMPLE 12 Into a 100 cc. autoclave, 20.4 g. (0.3 mol) of isoprene was charged, to which 0.44 g. of

obtained by the aforementioned process and 26 cc. of liquified butadiene were charged. An ethylene gas was introduced up to a pressure of 40 kg./cm. and the entire mixture was stirred at 85 C. for 6 hours. As a result, 2.1 g. of 1,5-hexadiene, 2.4 g. of 1,4-hexadiene, 1.3 g.

. 5 suspended in 10 cc. of xylene was added. Then 4 cc. (4 of and of rn mols) of a xylene solution of (C H AlCl was added. dlenes havmg 8 carbon atoms were Obtamed- When, at 80 C. under pressure of ethylene of 40 kg./cm. EXAMPLES 1521 the entire mixture was stirred for 1 hour, 24.90 g. of a I 20 f t 1 0 98 f mixture of 4-methyl-1,4-hexadiene with 5methyl-l,4- 10 n 0 Queue o hexadiene was obtained, The residue was 0.5 g. Conve'r- Fe[(C H PCH CH P(C H -C H slont: 95'00 (mol) percent Selectlvlty: 9 (mol) Was suspended, to which 2 cc, of the reaction mother Gen EXAMPLE 13 liquor obtained by the reaction of Example 1 was added, 15 and the entire mixture was heated at 70 C. for min- To a solution consisting of 0.357 g. of utes.

' The reaction solution was concentrated under a reduced Fe[(C6H5)2PCH2CH2P (C6H5 )212 C2H4 pressure and when diethyl ether was added thereto, 0.734 and 26 cc. of liquefied butadiene, 16 mmol of (C H A1 g. (77%) of was added and the mixed solution was heated to 80 C. and stirred for 6 hours while keeping pressure of ethylene 20 HFeHCGHQ (C6H5)PCH2CH2CP IC CH P C H at 40 kg./c m. As a result, 7.9 g. of 1,4-hexadiene was 6 5h 2 2 6 5h] obtained, besides which 1.0 g. of 1,5-hexadiene, 1.1 g. of was obtained. 1,3-hexadiene 0.4 g. of 2,4-hexadiene and 2.7 g. of octa- Into a 100 cc. autoclave, 26 cc. of liquified butadiene diene were formed. was charged, to which 0.424 g of EXAMPLE 14 6 4) 6 5) 2 2 6 5)2] (1) Production of 6 5)2 2 2 6 5)2] dissolved in 10 cc. of toluene was added. Furthermore HFeE(C6H4)(C6H5)PCH2C[I (I(HC CH P(C H 1 Lewis acids shown in the following table dissolved in 2 6 5 2 2 2 6 5 2 30 cc. of toluene were added thereto. The autoclave was Into a 100 cc. flask, 1.672 g. (0.0042 mol) of 1,2-bisheated to predetermined temperatures, pressure of ethyl- (diphenylphosphino)ethane, 0.707 g. (0.002 mol) of iron ene was kept at kg./cm. and stirring was continued (III) acetylacetonate and 20 cc. of benzene were charged, to obtain results shown in the following table.

{(HFeOtHi)(CBHQPCHZCHZHCnHQA Lewis acid Temp. Time 1,4-hexa- Residue Conversion Selectivity Ex. [(0011 )zPCH2CH;P(C H ](mm01) (mmol) C.) (min) diene (g.) (g) (mol percent) (mol percent) i8 23 a 2% 3-2 1 0. '12 (031153121 01 40 so 20 2312 014 8 '100 0.5 (otnnmiol 2.0 50 70 22. 55 0.7 100 95. 00 0.5 (C2H5)2A1C1 1.0 50 100 21.9 0.8 100 95.35 0.5 (nCaHuQAlClz 1.0 50 10 20.8 0.5 90. 34 96. 94 0.5 (110 110211101 4.0 so 20 23.1 0.8 100 05.59

to which 1.5 cc. of ethoxydiethylaluminum dissolved in EXAMPLE 22 15 cc. of benzene was added dropwise. During dropping the temperature was kept at 57 C. After dropping, the (1) In 15 of benzene of mixture was stirred at room temperature for 2 hours and Fe[(C H PCH CH P (C H 'C H heated at 650 for mmutes' Benzepe was hemmed was dissolved and the mixed solution was irradiated with under a reduced pressure and the reaction solution was a ultraviolet lamp (220 W.) for 3 hours. The reaction f i fg gggg ggfg g g' g i ig i f lg i g x 853 solllutioln gas concentrated under a reduced P IesSure and When this precipitate was recrystallized and purified from E zi g gg was added thereto 0'39 (yleld' 82%) a benzenediethyl ether solution, 1.2 g. (70%) of orange brown crystals of HFeHCs -Q (C6H5)PCH2CH2P(C6H5)2] HFEE(C5H4) 2] (C6H5)2] [(C H PCH CH P(C H was obtained.

was obtained. The melting point of the product was 179 (2) Into a 100 cc. autoclave, 10 cc. of toluene, 0.424 g. 180 C. 0 of The product was identlfied 3S ,E( 6 4 (CGHS)CHZCH2P(CGHS)2] H G Q( s 5) 2 2 6 5)2] s s z z e e s 2] e s) 2 2 2 s s 2] fol obtained by the aforementioned process, 13.0 g. of 2- as phenyl-1,3-butad1ene and 3 cc. of a toluene solution con- ObElemeital lanalyis.72g81l g 5 Egg-1 2 3 i? taining 4 mmols of diethylaluminum chloride were serve 1 ues n 24 F charged, and the mixture was stlrred at 80 C. under 3 Spectrum T e pressure of ethylene of 40 kg./cm. for 1 hour. As a reproton) sult, 10.3 g. of 4-phenyl-l,4-hexadiene was obtained.

(2) Production of non-conjugated diene: LE Into a 100 cc. autoclave, 30 cc. of toluene, 0.424 g. EXAMP 23 of Reaction of 0.70 g. of iron (III) acetylacetonate with HFe{-(C H )(C H )PCH CH P(C H 1.5 cc. of ethoxydiethylaluminum in the presence of 1,2 [(C H PCH CH P(C H bis(di-p-tolylphosph1no) ethane under the same conditions as described in the Example 14 gave 1.4 g. of the following complex. CH3 HFol om-Q-nr calcium-Q Elemental analysis: analytical values C, 74.71; H, 6.64. Observed values C, 74.98; H, 6.40.

Into a 100 cc. autoclave, 30 cc. of toluene, 0.23 g. of the iron complex obtained by the aforementioned method, 26 cc. of liquified butadiene and 2 mmols of diethylaluminum chloride were charged. The resultant mixture was stirred at 85 C. under ethylene pressure of 40 kg./cm. for 1 hour. As a result, 23.1 g. of 1,4-hexadiene was obtained. Conversion: 96.86 (mol) percent. Selectivity: 100 (mol) percent.

What is claimed is:

1. A process for producing non-conjugated dienes wherein ethylene is added to a carbon atom at position 1 or 4 of the starting conjugated diolefinic hydrocarbon, the said process comprising contacting a conjugated diolefinic hydrocarbon represented by the general formula R1 R1 R3 R4 HC=C-C=CH (wherein R R R and R stand for a hydrogen atom or a hydrocarbon group having 1 to 6 carbon atoms) with ethylene in the presence of at least one member selected from iron complexes of diphoshine represented by the general formula (wherein R stands for a hydrogen atom, a methyl group or an ethyl group It stands for 2 or 3, and R stands for a hydrogen atom or a hydrocarbon group having 1 to 6 carbon atoms) and iron complexes of diphosphine represented by the general formula (wherein R and n are the same as defined above) as a catalyst.

(wherein R stands for a hydrogen atom, a methyl group or an ethyl group, n stands for 2 or 3, and R stands for a hydrogen atom or a hydrocarbon group having 1 to 6 carbon atoms) and iron complexes of diphosphine represented by the general formula and (b) an organoaluminum compound.

3. A process according to claim 2 wherein molar ratio of an iron complex of diphosphine, the component (a), to an organoaluminum compound, the component (b), is within the range of 1:1 to 1:50.

4. A process according to claim 1 wherein the reaction is carried out under pressure of ethylene.

5. A process according to claim 1 wherein the reaction is carried out in the presence of a chemically inert organic solvent.

6. A process according to claim 1 wherein the said conjugated diolefinic hydrocarbon is 1,3-butadiene.

7. A process according to claim 1 wherein the said conjugated diolefinic hydrocarbon is 2-methyl-l,3-butadiene.

8. A process according to claim 1 wherein the said conjugated diolefinic hydrocarbon is 2,3-dimethyl-l,3-butadiene.

9. A process according to claim 1 wherein the said iron complex of diphosphine as a component of the catalyst is 10. A process according to claim 1 wherein the said iron complex of diphosphine as a component of the catalyst is P-omornP PCHaCHzP 11. A process according to claim 1 wherein the said iron complex of diphosphine as a component of the catalyst is 12. A process according to claim 2 wherein the said organoaluminum compound as a component of the catalyst is R"' AlCl (wherein R' stands for an alkyl group having 1 to 8 carbon atoms).

13. A process according to claim 2 wherein the said organoaluminum compound as a component of the catalyst is R"'3Al Cl (wherein R' stands for an alkyl group having 1 to 8 carbon atoms).

14. A process according to claim 2 wherein the said organoaluminum compound as a component of the catalyst is R'AlCl (wherein R' stands for an alkyl having 1 to 8 carbon atoms).

15. A process according to claim 2 wherein the reaction is carried out under pressure of ethylene.

16. A process according to claim 2 wherein the reaction is carried out in the presence of a chemically inert organic solvent.

17. A process according to claim 2 wherein the said conjugated diolefinic hydrocarbon is 1,3-butadiene.

18. A process according to claim 2 wherein the said conjugated diolefinic hydrocarbon is 2-methyl-1,3-butadiene.

19. A process according to claim 2 wherein the said 14 conjugated diolefinic hydrocarbon is 2,3-dimethyl-1,3-butadiene.

20. A process according to claim 2 wherein the said iron complex of diphosphine as a component of the cata- 21. A process according to claim 2 wherein the said iron complex of diphosphine as a component of the catalyst is li K HFe \PCH2CH2P \PCH2CH2P/ i 22. A process according to claim 2 wherein the said iron complex of diphosphine as a component of the catalyst is Fe /PCH2CH3CH2P\ -CH =CHg References Cited FOREIGN PATENTS 1,462,308 11/1966 France.

PAUL M. COUGHLAN, 1a., Primary Examiner U.S. Cl. X.R. 25243l; 260439 

